This invention relates to systems and techniques for monitoring fabrication processes of devices, for example, integrated circuit devices; and more particularly, in one aspect, to a system and technique that autonomously coordinates, synchronizes and/or correlates monitoring the operation of an integrated circuit fabrication process (or portion thereof) with respect to, or in connection with the data acquisition of one or more monitored parameters of the process.
Briefly, integrated circuits are typically fabricated on or in a semiconductor substrate that is commonly known as a wafer. A wafer is a substantially round, thin disk, currently having diameters such as four inches to twelve inches, and thicknesses in the range of two to three quarters of a millimeter.
During the fabrication processes, materials and/or layers are added, removed, treated and/or patterned on or in the wafer to form integrated circuits. In this regard, integrated circuit fabrication generally consists of a series of process stages, for example, photolithography, etch, strip, diffusion, ion implantation, deposition, and chemical mechanical planarization. At each step or stage, inspection(s) and measurement(s) is/are often conducted to monitor the fabrication equipment and materials, the individual processes, and interaction and integration among individual processes.
Monitoring-type equipment measure, evaluate and/or analyze selected/certain parameters on a processed production or test wafer in order to, among other things, measure, evaluate and/or analyze the integrity of the process(es). For example, certain conventional monitoring-type equipment may perform defect inspection, surface profiling, optical or other types of microscopy. Such monitoring often employs scanning electron microscopy (“SEM”) in measuring, evaluating and/or analyzing the integrity of the process(es). An SEM may require the wafer (production or test wafer) to be cross-sectioned in order to analyze its profile.
Another monitoring-type equipment is one that is disposed in the fabrication equipment in order to measure, for example, in real time, a parameter of the fabrication process. (See, for example, U.S. Pat. No. 4,585,342). During data collection or thereafter, the measured parameter may be analyzed. At the completion of processing, the real-time monitoring-type equipment may be removed from the fabrication equipment.
The real-time monitoring-type equipment employs real-time sensing circuitry that is often autonomous with respect to the fabrication equipment. In this regard, real-time monitoring-type equipment is typically untethered (i.e., not in communication with the fabrication equipment, and the control thereof). As such, the real-time sensing circuitry may have difficulty coordinating the measurement and recording of certain or selected events or processes performed by the fabrication equipment.
In addition, autonomous real-time monitoring-type equipment is often battery powered. That is, the real-time sensing circuitry, as well as collateral circuitry (memory storage and communication), are provided electrical power via rechargeable batteries. As such, limiting some or a significant amount of power consumption to correlate with the measurement and recording of certain or selected events or processes performed by the fabrication equipment will enhance the efficiency of power consumption. The consideration of power consumption is exacerbated where, for example, the real-time monitoring-type equipment that implements rechargeable batteries is only periodically or intermittently employed, where the fabrication equipment undergoes an extensive calibration routine prior to performing the fabrication process, or where heat generated by monitoring-type equipment could detrimentally effect or influence the process being monitored.